Such an extrusion device is used for dispensing compounds which are packaged in containers, such as mortar and sealing compounds, at a site of application. The containers include, for example, cartridges having one or more receiving chambers for one or more components of the compound to be dispensed which are provided directly or packaged, e.g. in foil bags, in the receiving chambers of the cartridge. The term “container” further includes foil bags which are filled with one or more components of the compound to be dispensed and which are inserted in a separate receiving body or in a receiving body mounted on the extrusion device.
When actuating the extrusion mechanism, an advancing mechanism acts on the at least one piston rod, advancing it by a predetermined amount. For example, a pressure piston attached to the piston rod acts on the compound contained in the container so that each time the piston rod is advanced, a corresponding amount of the compound is dispensed through a dispensing opening.
The extrusion mechanism may be operated mechanically (for example, using a trigger), electrically, or by a fluid (e.g., compressed air or hydraulic oil).
U.S. Pat. No. 4,461,407 describes an extrusion device for compound-containing containers, having a piston rod which is displaceable relative to the receiving chamber, and further having an extrusion mechanism including an advancing mechanism for advancing the piston rod.
The drawback of the known approach is that contaminants adhering to the piston rod, such as mortar remainders, may enter the advancing mechanism as the piston rod is advanced or retracted. Such contaminants or dirt may damage or even destroy the advancing mechanism. This reduces the life of the extrusion device.